The valves of this pump are formed by heavy rubber rings which surround the pump barrel, as shown in Fig. [423], therefore there can be no hammering of these valves when the pump is at work.
The rubber rings have slots cut into them at each side of each valve so that each valve can open and close without stretching the rubber bands. The steam valve is of the well-known rocker type. The plungers have no packing excepting water.
Fig. 425.—See page [122].
NOZZLES.
The sizes of nozzles named below will give the most satisfactory results, those in italics being the ones best adapted for fire duty. Also see page [93] for standard sizes of steam fire engines and page [117] for table of effective Fire Streams.
1, Extra first size engine.—1,100 to 1,150 gallons capacity. Through short lines of hose: One 11⁄2-inch smooth-bore nozzle, for one stream; one 13⁄4-inch ring nozzle, or one 2-inch ring: nozzle; 15⁄16-inch ring nozzles for two streams. With 1,000 feet of hose, one 15⁄16-inch ring nozzle.
2, First size engine.—900 to 1,000 gallons capacity. Through short lines of hose: One 13⁄8-inch smooth-bore nozzle, for one stream; one 11⁄2-inch ring nozzle, or one 15⁄8-inch ring nozzle; 11⁄4-inch ring nozzles for two streams. With 1,000 feet of hose, one 11⁄4-inch ring nozzle.